North Korea fired two ballistic missiles in a northeastern direction Monday, South Korea's military said, with one of the launches possibly failing and the missile landing inside the country. The Joint Chiefs of Staff (JCS) said one short-range ballistic missile was launched from the Jangyon area in South Hwanghae Province at about 5:05 a.m. and flew about 600 kilometers, landing in waters off the North's northeastern city of Chongjin. Another ballistic missile was launched from the same area at around 5:15 a.m. and flew only about 120 kilometers. Col. Lee Sung-jun, spokesperson of the JCS, told a briefing the second missile possibly flew abnormally in an early stage of its flight and that if it exploded in midair, its debris could have landed over North Korea. "It is difficult to know the missile's exact point of impact, but there is a possibility that it went toward Pyongyang," a JCS official said. The eastern part of Pyongyang is located about 120 kilometers northeast of the southwestern county of Ja ngyon. The North last launched two short-range ballistic missiles, known as the Hwasong-11, from the Jangyon area in March last year. The missiles flew about 610 kilometers to strike a target in waters off Chongjin, according to the North's state media. The JCS strongly denounced the latest launch as a "provocative act" that gravely threatens peace and stability on the Korean Peninsula, and vowed to maintain overwhelming readiness against such provocations. "While strengthening our monitoring and vigilance against additional launches, our military is maintaining a full-readiness posture while closely sharing North Korean ballistic missile data with U.S. and Japanese authorities," the JCS said in a text message sent to reporters. The launch came a day after the North's foreign ministry denounced a joint exercise between South Korea, the United States and Japan, saying the country would take "offensive and overwhelming" countermeasures against what it called an attempt to strengthen a military bloc. The th ree-day multidomain Freedom Edge exercise, which ended Saturday, involved fighter jets and warships, including a U.S. aircraft carrier, in international waters south of South Korea's southern resort island of Jeju. The latest launch also took place five days after the North's firing of a ballistic missile toward the East Sea on Wednesday. The North claimed the next day to have successfully conducted a multiple warhead missile test, but the South has dismissed the claim as "deception," saying the launch ended in failure as the missile exploded in midair. The latest launch also took place amid growing concerns over deepening military cooperation between Pyongyang and Moscow after North Korean leader Kim Jong-un and Russian President Vladimir Putin signed a "comprehensive strategic partnership" treaty during a summit last month in Pyongyang. The pact includes a pledge for the two countries to come to each other's aid if attacked. The launch raised speculation the missiles could possibly be a test for those intended to be sent to Russia. Lee declined to comment when asked about the possibility. Seoul and Washington have accused Pyongyang of delivering arms to Moscow to fuel its war against Ukraine. Defense Minister Shin Won-sik has said arms trade between North Korea and Russia is expected to expand after their leaders' signing of the treaty. North Korea has ratcheted up cross-border tensions in recent weeks, launching trash-carrying balloons to South Korea in a tit-for-tat move against anti-Pyongyang leaflets sent by North Korean defectors and activists in the South. Source: Yonhap News Agency